Press brake control



June 29, 1965 c. E. DUVALL 3,191,412

PRESS BRAKE CONTROL Filed June 25, 1962 Ill Ililmlllllllllllllllllllllllliil /NVEN7'OR CLARENCE E. DUI/ALL United States Patent 3,191,412 PREEES BRAKE CQNTRGL (liar-once E. Duvall, 3503 N; ElVista Ave, Peoria, Ill. Filed June 25, 1962, Ser. No. 284,799 8 Claims. (Cl. 72-26) This invention relates to'a press brake control and more particularly to a semi-automatic control to adjust the effective depth of stroke of a conventional press brake rapidly and accurately.

In conventional press brake operations, it is necessary to adjust the depth of the stroke of the ram to vary the angle of bending and to accommodate different gauges of metal. For example, in forming of a single piece, bends at two or more angles may be required which means either that the depth of stroke must be adjusted two or more times as each piece is formed or that a series of pieces must be run with one setting and then rerun with each different setting. This last procedure involves handling of each piece a number of times and is not economical.

Press brakes have heretofore been constructed with motor operated selector mechanisms to adjust the depth of the stroke under control of a manually operated switch. However, even with such mechanisms, setting of the brake has been very difficult and time consuming and has required considerable jogging of the control to achieve the proper setting.

It is accordingly an object of the present invention to provide a press brake control which operates semi-automatically to set the depth of stroke of the ram to any one of a plurality of diilerent positions rapidly and accurately.

Another object is toprovide a press brake control which can be adjusted easily and quickly to change the set positions or to accommodate dir'ierent gauges of metal.

Still another object is to provide a press brake control which can easily be installed on existing press brakes.

The above and other objects and features of the invention will be more readily apparent from the following description when read in connection with the accompanying drawing, in which:

FIG. 1 is a perspective view of a press brake of more or less conventional construction equipped with a control embodying the invention;

FIG. 2 is an end elevation of a rotating drum and switch assembly according to the invention;

PEG. 3 is a side elevation with parts in section of the drum and switch assembly of FIG. 2;

FIG. 4 is an enlarged partial side elevation of the drum illustrating the scale mounting; and

FIG. 5 is a diagrammatic view of the control circuit embodying the invention.

The invention, as shown in FIG. 1, is applied to a more or less conventional press brake having a bed supported on a base or frame 11 and adapted to hold a bottom bending die of any desired construction. The frame includes upright side members 12 on which vertically slidable slides 13 are movable. The slides are adapted to be shifted vertically through a predetermined stroke by a motor 14 connected through suitable sprockets or gearing to eccentrics which are connected for rotation, together with a shaft 15- running beneath the bed. The eccentrics are connected to the slides 13 to move them vertically toward and away from the bed.

The slides adjustably carry a ram 16 on which the upper bending die is supported for movement toward and into the lower bending die. The ram is adjustably connected to the slides for vertical movement relative thereto so that the depth of the stroke may be adjusted thereby to control the degree of bending of the Work. Conventional adjusting mechanism is employed for this pur- "ice pose which'as shown includes rotatable pinions 17 at 09- posite sides of the machine which are geared together through a cross shaft 13. When the pinions are rotated they may turn adjusting devices, such as cams or eccentrics, through which the ram is connected to the slide thereby to adjust the vertical position of the ram relative to the slides. Since the stroke oi the slides is fixed, adjustment of the ram relative thereto will vary the depth of stroke of the ram thereby to vary the degree of penetration of the upper die into the lower die to change the angle through which the metal being worked upon will be bent. The mechanism as so far described is conventional and will vary to some extent from one press brake to another. Since this mechanism, per se, forms no part of the present invention it will not he described in further detail herein.

In the press brake, as shown, the ram is adjusted by a reversible electric motor 19 mounted on one of the slides for movement therewith and connected through reducing gearing to. the shaft 18 to turn it in one direction or the other thereby to adjust the depth of the stroke of the ram. A manually operable reversing switch 21 is preferably provided having an operating handle 22 movable in one direction to raise the stroke of the ram and in the opposite direction to lower the depth of the stroke of the ram. In the conventional operation this reversing switch may be manually controlled to move the ram to a desired position, but because of overrun or coast in the motor and associated parts and because of the difficulty of reading the setting, it has been found to be extremely difficult to adjust the stroke rapidly or accurately under manual control.

The present invention provides a semi-automatic control for adjusting the depth of stroke of the ram, including a relay indicated generallyat 23 which is provided with a manual or automatic selector switch 24- and with a push button start switch 25. Preferably the relay also includes a signallight 26 to indicate when the adjusting mechanism is operating.

The control circuit also includes a plurality of normally open switches 27 which are closed by cam fingers adjusted according to the desired settings of the press brake. As best seen in FIGS. 2 and 3, the switch operating mechanism includes a sheet metal drum 28- secured to one of the pinions 17 to rotate therewith and projecting axially therefrom. The drum 28 is formed with one or more circumferentially extending slots 29 therein adjustably to mount actuating fingers 31. The fingers may be adjustably secured to the drum by screws 32 extending through openings in the fingers and through the slots in the drum and secured in adjusted position with respect to the drum by nuts on the inner ends thereof. In this way, by loosening the screws the fingers can be slid circumferentially around the drum to desired positions and can be secured in such positions by retightening the screws so that they will be accurately held. The switches may be mounted in desired angular positions on an arcuate sheet metal flange 33 secured to a plate 34 forming a part of the cover'for the pinion 17 and the entire switch mechanism may be enclosed in a sheet metal housing 35 at one side of the machine, as shown in FIG. 1.

In order to indicate the desired positioning of the fingers for different bending operations, a scale strip 36 is pro vided graduated in degrees of bend from 0 to and extending circumferentially of the drum with its graduated edge portion projecting beyond the end of the drum to be easily visible. In the construciton shown, there are two slots 29 arcuately spaced around the drum with a separate scale strip for each slot, although by positioning the switches differently, both of the fingers could be mounted in the same slot and could be adjusted accordlg to the same scale. hile only two switches 27 have been shown to set the am for two different depths of stroke, additional switches 3 provide additional settings up to any reasonable numer which can be accommodated by the physical dimenions of the unit could be employed.

The graduated strips 36 are adapted to be adjusted anularly around the drum in accordance with different auges of the metal to be bent. As shown, the drum self is formed with graduations 37 corresponding to the iiferent gauges of metal to be bent in the particular iachines and the scale strip 36 is provided with a refernce mark 38 corresponding to zero bending which can e read against the scale 37. The scale strip may be rictionally supported for movement around the drum n any desired manner and is shown as being held by clips 9 secured to the inner surface of the drum and extend- Jg over the inner surface of each scale strip.

The several parts of the control are connected in a ontrol circuit, as shown in FIG. 5. Lines 41 extend mm a suitable source of power into the relay 23 through .ormally closed relay switches 42 which are opened when he relay coil 43 is energized. The switches 42 when losed connect the power lines directly to the reversing witch 21, as shown. The relay coil is connected in ircuit with the manual selector switch 24 and with the tart switch 25 which is normally closed and with the tormally open switches 27 which are connected in parallel vith each other. The indicator lamp 26 is connected in he circuit, as shown, to be energized whenever the selecor switch 24 is closed to indicate that the control is in ondition for automatic operation.

In operation with the ram adjusted as, for example, to

he position shown in FIG. 2 the right-hand switch 27 vill be closed by engagement with the finger 31. If the manual selector switch 24 is closed at this time to select iutomatic operation and the normally closed start switch is closed, a circuit will be completed to the relay coil L3 to energize it and to open the relay switches 42 so that he motor 19 will be de-energized. The ram will thereore remain in the position to which it is adjusted as, for xample, the position to produce a 90 angular bend in workpiece of 24 gauge with the indicator strip 36 posiioned as shown in FIG. 4 relative to the indications 37. When it is desired to change to a different angular bend or which the left-hand finger 31 is adjusted, the reversing witch 22 will be turned in a direction to operate the motor 19 to raise the ram thereby to reduce the angle of end. To accomplish this the start switch is pressed 0 open it thereby interrupting the circuit to the relay oil 43 so that the switches 42 will close to energize the notor 19 through the reversing switch. At this time, he gear 17 and drum 28 will turn counter-clockwise, as een in FIG. 2, and will continue to turn even after the tart switch 25 is released until the left-hand finger 31 ngages and closes the left-hand switch 27. This may be .u adjustment, as shown in FIG. 4, for a 60 bend, for xample. As soon as the left-hand switch is closed, the elay coil 43 will again be energized to open the relay witch 42 and de-energize the motor 19. The parts may emain in this condition until it is again desired to adjust he ram at which time the process as described above may be repeated with the reversing switch being set for mention in the proper direction.

Where more than two switches 27 are employed the lperation is similar to that above described, except that he reversingswitch might be left in the same position vith the starting switch being again opened temporarily 0 cause the drum to continue turning in the same direction intil a second finger in the same slot engaged and closed )ne of the switches 27. It will thus be seen that the nechanism is not limited to setting of the press brake n two positions only, but can be utilized to produce .djustments in substantially any desired number of dilfer- :nt positions.

It will be appreciated also that i While one embodiment of the invention has been shown and described herein, it will be understod that it is illustrative only and not to be taken as a definition of the scope of the invention, reference being had for this purpose to the appended claims.

What is claimed is:

1. In a press brake having a bed adapted to hold a die, a ram adapted to hold a complementary die, power operated means connected to the ram to move it through a predetermined stroke toward and away from the bed, and means to adjust the ram relative to the power 0perated means thereby to adjust the movement of the ram toward the bed, bending control means comprising a motor connected to the adjusting means to move it, a rotatable drum drivably connected to the motor to be driven thereby to a position corresponding to the position of the ram relative to the power operated means, a pair of switches mounted adjacent to the drum and operably connected to the motor to stop it when either switch is actuated, at least one finger adjustabiy mounted on the drum and engageable with the switches selectively to actuate them when the drum is rotated to different angular positions, and a manually operable switch operably connected to the motor to energize it regardless of the actuated condition of the first named switches.

2. The construction of claim 1 including a manually operable reversing switch connected to the motor to select tie direction of operation thereof.

3. In a press brake having a bed adapted to hold a die, a ram adapted to hold a complementary die, power operated means connected to the ram to move it through a predetermined stroke toward and away from the bed, and means to adjust the ram relative to the power operated means thereby to adjust the movement of the ram toward the bed, bending control means comprising a motor connected to the adjusting means to move it, a rotatable drum drivably connected to the motor to be driven thereby to a position corresponding to the position of the ram relative to the power operated means, a pair of switches mounted adjacent to the drum, at least one finger adjustably mounted on the drum selectively to engage the switches to close them, a power supply circuit for the motor, a relay in the circuit including a normally closed switch through which the motor is energized and which is opened when the relay is energized, and a control circuit for the relay including said pair of switches in parallel with each other and a normally closed, manil allyopenable switch in series with said pair of switches.

4. In a press brake having a bed adapted to hold a die, a ram adapted to hold a complementary die, power means connected to the ram to move it through a predetermined stroke toward and away from the bed, and

mechanism including a rotatable pinion to adjust the ram relative to the power means thereby to adjust the movement of the ram toward the bed, bending control means comprising a motor connected to said mechanism to move it to different adjusted positions, a drum mounted on said pinion to rotate therewith, a plurality of switches mounted adjacent to the drum, at least one finger mounted on the drum to engage and actuate the switches in different angular positions of the drum, a control circuit for the motor including said switches to stop the motor when any one of the switches is actuated, and a manually operable switch in the control circuit operable to energize the motor regardless of the actuated condition of one of the first named switches.

5. The construction of claim 4 in which the drum is formed with a circumferentially extending slot in which the finger is slidable and the finger is formed to clamp itself in any selected position along the slot.

6. In a press brake having a bed adapted to hold a die, a ram adapted to hold a complementary die, power means connected to the ram to move it through a predetermined stroke toward and Way from the bed, and mechanism including a rotatable pinion to adjust the ram relative to the power means thereby to adjust the movement of the ram toward the bed, bending control means comprising a motor connected to said mechanism to move it to different adjusted positions, a drum mounted on said pinion to rotate therewith, a plurality of switches mounted adjacent to the drum, at least one finger mounted on the drum to engage and actuate the switches in different angular positions of the drum, a relay having normally closed contacts in circuit with the motor and which are opened when the relay is energized, and a control circuit for the relay including said first named switches in parallel with each other and a normally closed manually openable switch in series with the first named switches.

7. In a press brake having a bed adapted to hold a die, a ram adapted to hold a complementary die, power means connected to the ram to move it through a predetermined stroke toward and away from the bed, and mechanism including a rotatable pinion to adjust the ram relative to the power means thereby to adjust the movement of the ram toward the bed, bending control means comprising a motor connected to said mechanism to move it to difterent adjusted positions, a drum mounted on said pinion to rotate therewith, a plurality of switches mounted adjacent to the drum, at least one finger mounted on the drum to engage and actuate the switches in ditferent angular positions of the drum, the drum being provided with circumferentially spaced graduations graduated in different gauges of metal to be bent, an indicator strip slidable circumferentially of the drum relative to said graduations and graduated in angular degrees to indicate proper setting of the fingers for predetermined angular bends, and a control circuit for the motor including said switches to stop the motor when any one of said switches is actuated.

8. In a press brake having a bed adapted to hold a die, a ram adapted to hold a complementary die, power means connected to the ram to move it through a predetermined stroke toward and away from the bed, and mechanism including a rotatable pinion to adjust the ram relative to the power means thereby to adjust the movement of the ram toward the bed, bending control means comprising a motor connected to said mechanism to move it to different adjusted positions, a drum mounted on said pinion to rotate therewith, a pair of switches mounted adjacent to the drum and spaced circumferentially thereof, the drum being formed with a pair of circumferentially extending slots traversing the switches respectively as the drum turns, actuating fingers adjustably mounted in the respective slots to engage and actuate the switches respectively as the drum is turned to different angular positions, the drum being formed with a scale graduated in different gauges of metal to be bent, indicator strips adjustable circumferentially of the drum adjacent to the slots and graduated in angular degrees to indicate proper setting of the fingers for different angular bends, and a control circuit for the motor including said switches to stop the motor when either of said switches is actuated.

References Cited by the Examiner UNITED STATES PATENTS 2,290,626 7/42 Bosomworth.

2,543,759 3/51 Cannon et a1. 153--21 2,793,584 5/57 Pearson 153-21 XR 2,797,724 7/57 Walldow 15321 CHARLES W. LANHAM, Primary Examiner. 

1. IN A PRESS BRAKE HAVING A BED ADAPTED TO HOLD A DIE, A RAM ADAPTED TO HOLD A COMPLEMENTARY DIE, POWER OPERATED MEANS CONNECTED TO THE RAM TO MOVE IT THROUGH A PREDETERMINED STROKE TOWARD AND AWAY FROM THE BED, AND MEANS TO ADJUST THE RAM RELATIVE TO THE POWER OPERATED MEANS THEREBY TO ADJUST THE MOVEMENT OF THE RAM TOWARD THE BED, BENDING CONTROL MEANS COMPRISING A MOTOR CONNECTED TO THE ADJUSTING MEANS TO MOVE IT, A ROTATABLE DRUM DRIVABLY CONNECTED TO THE MOTOR TO BE DRIVEN THEREBY TO A POSITION CORRESPONDING TO THE POSITION OF THE RAM RELATIVE TO THE POWER OPERATED MEANS, A PAIR OF SWITCHES MOUNTED ADJACENT TO THE DRUM AND OPERABLY CONNECTED TO THE MOTOR TO STOP IT WHEN EITHER SWITCH IS ACTUATED, AT LEAST ONE FINGER ADJUSTABLY MOUNTED ON THE DRUM AND ENGAGEABLE WITH THE SWITCHES SELECTIVELY TO ACTUATE THEM WHEN THE DRUM IS ROTATED TO DIFFERENT ANGULAR POSITIONS, AND A MANUALLY OPERABLE SWITCH OPERABLY CONNECTED TO THE MOTOR TO ENERGIZE IT REGARDLESS OF THE ACTUATED CONDITION OF THE FIRST NAMED SWITCHES. 